Pressure Difference Between Brain and Eye: a Possible Cause to Normal Tension Glaucoma.

Normal Tension Glaucoma Clinical Trial

Official title: Pathological Cerebral Venous Drainage System Giving Large Pressure Difference Between Brain and Eye at Upright Posture: a Possible Cause to Normal Tension Glaucoma.

Status Completed

Clinical Trial Summary

The main aim of this study is to determine the trans-laminal cribrosa pressure difference (TLCPD) for normal tension glaucoma (NTG) patients from the brain and the eye in supine, upright and minor head down tilt positions. It is also to investigate the venous drainage system in the same body positions.

Clinical Trial Description

The trans-lamina cribrosa pressure difference (TLCPD), i.e. the difference between the intraocular pressure (IOP) and the intracranial pressure (ICP) has been suggested as a pathophysiological component in glaucoma. The theory is that high TLCPD, either due to elevated IOP or reduced ICP, can cause glaucomatous damage.

Normal tension glaucoma (NTG) patients has been found to have a slightly reduced ICP when measured in horizontal position. However, in a previous study in healthy adult volunteers the investigators have measured TLCPD at supine, sitting and 9 degree head down tilt positions and found that the TLCPD was posture dependent, with the largest difference in the upright position. Since humans are upright approximately two thirds of the day, one can expect that TLCPD in a diurnal perspective is primarily influenced by the ICP in the upright position.

In this study the TLCPD in different positions in patients with NTG will therefore be measured.

The study will be carried out in three parts.

1. TLCPD will be investigated by simultaneous measurements of IOP and ICP. For IOP the Applanation resonance tonometer (ART), developed by our research group, will be used. ART is independent of gravitation and possible to use in all body postures. In this study measurements will be performed in supine, sitting and head down tilt positions. ICP is measured continuously during the period of body position changes with a CELDA lumbar pressure measurement apparatus.

2. Brain and eye MRI investigation will be performed at a 3 Tesla GE scanner with a new generation 32-channels head coil. The images will be used to measure the cross-section area, the blood flow velocity and the flow direction in the jugular veins, as well as the structural properties of the optic nerve and optic nerve head.

3. Ultrasound imaging, using a high-resolution apparatus, will be performed to study the effects of postural changes on the blood flow velocity and the cross-section area of the right and left internal jugular veins and external jugular veins. ;

Related Conditions & MeSH terms

• Glaucoma
• Low Tension Glaucoma
• Normal Tension Glaucoma

• NCT number: NCT02776449
• Study type: Observational
• Source: Umeå University
• Status: Completed
• Phase: N/A
• Start date: February 2016
• Completion date: June 2016